Deflection circuit



May 3, 1960 M. LEEDS `2,935,644

DEF'LECTION CIRCUIT Filed April 28, 1959 3 Sheets-Sheet 1 May 3, 1960 M. LEEDS 2,935,644

DEFLECTION CIRCUIT Filed April 28, 1959 3 Sheets-Sheet 2 FIG. 2

f LANxme 'i nea-'femm JNVENTOR.

Laurence MLeeds Byvnne.

3 Sheets-Sheet 3 May 3, 1960 l.. M. LEEDS A DEFLEc'rIoN CIRCUIT Filed April 28, 1959 INVENTOR. Louronce M. Leeds ATTORNEJ Mu/dam M.

" y its deflection cycle would be non-linear.

United Strescpatem 2,935,644' nEFLEcrIoN CIRCUIT Laurauce Leeds, Syracnse,N.Y., assignor to General Electric Company, a corporation of New York Application April 28, 1959, Serial No. 809,566 11 Claims. (ci. sis-27) This invention relates to cathode ray deiiection circuitsl andpis particularly directed to `such deii'ection circuits Y having improved linearity of line rate of scanning.

`It Vvhas been the practice in detiection circuits of this i itypeto provide anv electron discharge tube having azrelf ativelyerhigh power output for supplying energy to the beam deiiecting coils. Across these deflection coils there is usually connected adamping device, the purpose of which is to eliminateY` high frequency oscillations which are otherwise set up in the deecting coils during retrace time and also to aid in the deection of the cathode ray during apart of each deiiection cycle. The damping device` serves as Va periodic discharge path` .for lthe electromagnetic energy stored in the vdeiiectingV coilspr l other crcuitinductance at the end ofthe deflection cycle', s In the absenceof the damping device, this stored energy fr would normally produce relatively high frequency oscillations in the system with the concomitant result that the deection of the cathode ray during the initial part of When a damping device isso used, only one-half cycle of such free oscillation is permitted to take place and thereafter .the energy .contained inthe deiiecting coils or other'circuit partof the next-deinductance is used forthe initial ection cycle.

When a; power tube .and damping device are used Vin the above described manner, the circuit constants have normally been chosen such thatthe power tube does not supply energy at least during approximately the iirst v 30% of the deiiection cycle and the damping device is usually rendered non-conductive at least during approximately the last 30% or so of the cycle. It hasv been found that the summation characteristic of the output of the power tube andthe damping device is not linear and 'consequently,distortion of the reproduced image may Y occur. To overcome this non-linearity, various feedbackl arrangements have been u sed such as from the deiiection l coils or transformer secondary/to the deflection wave generator or to the input to the power tube respectively. Such feedback `arrangements have improved somewhat the linearity of the liney rate scanning and since use for television up to now'has been essentially in the `iield of entertainment, the linearity of scanning provided by known .deflection circuits employingv the above described feedback has been relatively adequate.

However, many new applications for'television systems are now developing in fields other than that of entertainment. Many of these applications utilize a singleV tube Y Vcamera either in a monochrome or in a iield sequential systerrn In some ofthe newer applications such as v those thatinvolve the pick-up of maps, characters, coordinates and related information, etc., it has become essential that the line rate scanning be substantially perfectly linear.

. Also, in the iield of color television wherein livercolorv television pick-up utilizes a camera vemploying three image orthicon tubesin which the electron beams are deliected simultaneously, each of the tubes beingresponsive to one VAilection system will tend -to destroy the registration with. consequent color fringing and picture degradation.

of the. three primary colors in order to obtain an accept- 1 able color picture withadequate resolutiomit is essentialA s that the three pictures be precisely'registered. `Since the deflection coils cannot be exactly .identicalnor can theV camera tubes be precisely equal in their'deiiection sensi;

tivity, it has been the common practice in`v this situation to provide each of the deflection coils with differential.

controls for size, skew and Q and to drive thefthree deiiection coils and their associated differential 'circuits with a common deflection system. Here agaimany inf; stability or drifting of any portion of theY entire dethe deiiection circuit throughout the wholeY deflection period to correct for any drifting in the circuit.

Another important feature of the invention is the use of negative feedback to automatically correct the ,waveaof predetermined the current in thedeflection coils to a linearity.

Generally speaking in accordance with the invention-,1 there is provided a deilecting circuit for' a cathode rayv comprising a source of cyclically varying current, a transformer having a primary winding and a secondary winding, the primary winding being connected to the source or 'cyclically varying .current and a cathode ray deiiece tion coil connected in shunt with'the secondary winding. The current through the coil increases toa predetermined value in accordance with the increase in current from' the source, the current from the source being cut offa'fter the current through the coil rises to; the predetermined valuer whereby the current in the deflection coil circuit after rising to such predetermined value isset into oscillation atV a frequency determined `by the eiective inductance and capacitance of the deflection Vcoil circuit. An electron discharge device having atleast a cathode control electrode and an anode for damping these cui- 's rent oscillations' after the yfirst-half cycles ofsuch oscil= lations is connected so as to have its anode'to cathode s Y I path in shunt with the secondary winding. 'Ihe source of cyclically varying current comprises means forrgen eratng a cyclically varying potential, means responsive to the application thereto of the cyclically varying poten; tial and a potentiai proportional to the current 'flowing through the coil for providing a potential in accordance with a ydifference therebetween, a power tube having an' input and an output circuit, means for applying Vthe output of the difference means to the input circuitV of the power tube and to the control electrode of the damping device,

the v'transformer coupiing the output ofthe power tubje to the deflection coil. The power tubeandtlie damping discharge device are chosen to Ahave respective'operating points such that there is sufficient overlap in their* respecV tive conductions in the region of the centeroffthe scarl sion such that conduction vs'ilibsists throughout substani tially the entire Scansion period between thee'nd of one of the first-half cycles of the oscillations and the be` ginning of the next of the first-half cycles of Ythe oscillations whereby the overall feedback is, eiective'over substantially the entire sweep cycle. Effectively, the cirfiV cuit is class AB operated,- the power tube beingconductive" at least during the latter half of the scansionv period l2,91at644 Patented MayS,

and the damping discharge is conductive during at least the first-half of the aforesaid scansion period.

The novel features, which are believed to be characteristic of this invention, are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation together with further objects and advantages thereof may best be understood by reference to the following description taken in connection with the accompanying drawings.

In the drawings, Fig. 1 is a schematic representation of a deflection circuit embodying my invention and which is adaptable for use in a single tube camera system.

Fig. 2 is a group of diagrams utilized to explain the operation of the embodiment of this invention shown in Fig. 1; and,

Fig. 3 is a schematic depiction of a deection circuit embodying my invention which may be used with a three tube camera system such as is found in the field of color television.

vReferring now to Fig. 1 wherein there is shown a circuit embodying my invention and adaptable for use in a one tube camera system, that portion of the circuit enclosed by the dashed line and designated by the numeral is a means for generating a cyclically varying potential such `as a voltage wave having a saw tooth configuration. It comprises an electron discharge tube 12 having a cathode 14, a control grid 16 and a plate 18. The cathode 14 -is grounded and plate 18 is connected to a source 20 of B+ potential through a resistor 22, a-resistor 24 having a switch 25 thereacross to enable its being removed from the circuit, and a variable resistor 26 which is connected to ground through a resistor 28. Shunting tube 12 `are a capacitor 30 `and a difierential modification circuit comprising a capacitor 32 and a variable resistor 34, one end of resistor 34 being connected to ground. In accordance with the operation of saw tooth wave generators, tube 12 is so biased as to normally be non-conductive in its quiescent state. During such non-conductive period, capacitor 30 charges. Upon the application of a discharge pulse to tube 12, it is rendered conductive permitting capacitor 30 to rapidly discharge therethrough. The circuit comprising capacitor 32 and variable resistor 34 functions as a limited range predistortion circuit in that it modifies the substantially linear saw tooth wave output of tube 12 by applying a controlled small amount of curvature during approximately the first 20% of the scansion Wave form. As will be further explained hereinbelow, it is during this time that the damper device is operating at its utmost to correct, under the control of the negative feedback, the resultant yoke, i.e., the deflection current to a linear saw tooth form. Since the amount of such correction required utilizes the feedback to its limit, by inserting a small and controlled amount of predistortion, the negative feedback is greatly increased in effectiveness. As will also be further brought out hereinbelow, such insertion of small and controlled amount of predistortion permits a fine control for differential linearity at the left hand side of the picture, i.e., the start of scansion. The arrangement of resistor 22, removable resistor 24, and variable resistor 26 permits the size of the generated saw tooth wave resulting from the operation of generator 20 to be varied between wide limits. The pulses applied to control grid 16 for rendering tube 12 periodically conductive to discharge capacitor 30 may suitably be obtained from a self-blocking oscillator (not shown) or like pulse generating device. Such pulse generating device may be driven, for example, in a television system by the horizontal drive pulse.

The output of saw tooth wave generator 10 is applied through a capacitor 35 to the input of a difference amplifier designated by the numeral 40. Difference amplifier 40 comprises an electron discharge tube 42 andan electron discharge tube 44, suitably contained in a single 4 envelope, and their respective associated circuit elements. Tube 42 with its associated circuit elements is a conventional amplifier and tube 44 with its associated circuit elements is a cathode follower. Cathodes 46 and 48 are connected to ground through common series arrangement of resistors 47 and 49 and plates 50 and 52 are connected to B+ source 20 .through resistors 54 and 56 respectively, resistor 56 being chosen to have a relatively small value. The input to control electrode 58 through a resistor 59 is a positive going voltage of saw tooth configuration and having a predetermined linearity to which the output of the system corrects itself. The input to control electrode 60 through a resistor 65 is a positive going voltage of substantially s-aw tooth configuration from the deflection coil which is proportional to the current passing through such coil. The output appearing at plate 50 is the negative going voltage of saw tooth .configuration which is proportional to the difference between the input voltages to the difference amplifier 40. Effectively, difference amplifier may be dgnated in this situation Vas a feedback mixer.

The output of difference amplifier is applied through a capacitor 62 to the grid 83 of a degenerative amplifier designated by the numeral 70. Amplifier 70 comprises an electron discharge tube 72 having a plate 74 connected to B+ source 20 through a resistor 76 and also connected to the B+ source through a variable resistor 78, the cathode 80 being grounded through an unbypassed resistor 82.

One output of amplifier 70 which is a positive going sau/ tooth voltage is applied to the input of a power amplifier. Another output is taken from a point on variable resistor 78 and applied through 4a capacitor 88 to an `amplifier 90. Amplifier 90 comprises a first degenerative amplifier comprising an electron tube 91 having a plate 92 connected to B+ source 20 through a resistor 94 and a cathode 96 connected to ground through an unbypassed resistor 98. The input from variable resistor 78 is applied to a control grid 100. The output at plate 92 which is `a negative going saw tooth voltage is applied through a capacitor 102 to the control grid 104 of an electron tube 106 connected as a cathode follower. Plate 108 of tube 106 is directly connected to the B+ source 20 and cathode 110 is connected to ground through resistor 112. It is to be noted that the return of grid 104 to the B+ source through resistor 103 providesV for linear large signal excursion. It is seen that if grid 104 were returned instead, for example, to ground, cathode 110 would still be positive but such large signal excursion could not occur since the signal would be clipped quite quickly.

The output at cathode 110 is applied to a damping electron discharge device through a capacitor 114 as will be further explained hereinbelow.

Power amplifier to which the output is applied from plate 74 through a capacitor 121 includes a power tube 122 comprising a plate 124 connected through a resistor 126 to the high potential end of primary windingV 130 of a transformer 128, and through primary winding 130 and a resistor 134 to B+ source 20. Oathode 136 is connected to ground through a resistor 138 bypassed by a capacitor 140. The suppressor grid 142 is tied to cathode 136 and the screen grid 144 is connected to the B+ source through resistor 146 and a resistor 148, the junction of resistors 146 and 148 being grounded through a capacitor 150. The circuit values of the components associated with power tube 122 are so'chosen as to maintain conduction throughout approximately the latter 65 or 70% of the rising portion of the saw tooth wave produced by generator 10; i.e., conduction in power tube 122 ceases at the initiation of yback and is not resumed until a time corresponding to vabout 1;/3 of the scansion cycle.

Secondary Winding 132 has one end thereof connected to the plates and 162 of damper electron discharge through the deiiection coil 176.

#current in the'circuit of Fig. 1. i l Referring now to the operation of the circuit of Fig. l,

@approximately during the devies 14. The @treffend :of secondary winding 132 is grounded'through a capacitor 153 and is Yconnectehdvby atap-'to a point on variable resistor' 170.

An intermediate point 1 74 on secondary winding` 132 is connected to one terminal 175 of a cathode ray deection cil 176, the other terminal 177 of deection coil1'76f being connected through an inductance 1178- and y 'by a tap to a point on variable resistor 172. Terminal 177 is also connected to ground through a capacitance 180'. Damper discharge device V154 includes cathodes 161 and 163 which'are grounded andi isolating resistors 4v181v and 183 through which the output from the cathode 110 at tube-106 is simultaneously applied to Ycontrol'gricls 165 and 167 through capacitr 114;

' In considering the operation of the device of Fig. 1 it'isconvenient to examine the graphs shown in Fig. 2 inv connection with the Vexplanation of such operation.

v Ingraph A, the abscissa represents time and the ordinate represents the general form of the voltage pulse applied to the input of tube 12 of saw ltooth wave generator 10i.v

, In graphv B the abscissa represents time and the ordinate represents the voltage appearing at plate 18 and at conl trol grid 58." .I Y In graph C, the abscissa represents time and the ordinate represents vthe voltage appearing at theplate of tube 42 and at the control grid 83 of tube 72. In graph D, lthe, abscissa represents time and the ordinate represents the voltage appearing at the plate 74 of tube 72 and at y the grid-145 of power tube 122, lineD2 indicating the level that above which tube 122 conducts. In graph E, the abscissa represents time and the ordina-te represents the voltage appearing at the cathode 110 of tube 106,

- and at the grids 165 and 167 of damper device 154, line Ezindicatingthe level below which the damping device is rendered non-conductive. In graph F the abscissa represents' time and the ordinaterepresents current llowing The graphs of Fig. 2 are drawn to the same time scale -andpoints on the graphs lying in a straight line perpendicular to the time axisfrepresent generally simultaneous conditions of voltage-and a positive going saw tooth voltage represented by graph l 'BV of Fig.- 2 is applied to grid 58 of tube 42. Simultaneously a feedbaclevoltage proportional to the current ilowing through deflection coil 176 is applied to grid 60 of tube 44. The voltage appearing at plate 50 depicted in graph C of Fig. 2 is applied to the input of degenerative ampliiier 70. The Voutput of ampliiier 70 which is a positive going saw` ,t`ooth having the configuration as depicted in graph D of Fig. 2 is applied simultaneously Ito the input of power amplifier 120and via a'tap Aon variable plate resistor 78 to the input of tub'e91. The inverted output from the latter is applied to' cathode follower tube 106 and the negative going saw tooth voltage produced therefrom is applied to both grids of the damping device 154.

The output of power tube 122 is applied to the privmary winding of transformer 128, the current flowing 'through secondary winding 132 drivingthe deection *coil 176. Since at the time t1 Vrepresented by the maxi- -mum point of the saw 1tooth voltage from generator 10, fthe lvoltageV on the control grid 145 of power amplifier "tube 122 is driven in a negative direction Very rapidly Yresulting in complete cut-od, thereof, Aa self-oscillation is caused in the transformer deilection coil circuit at a frequency deternfrined approximatelyv bythe self-inductance of deilection coil 176 and allaof lthe-dis.trib uted capacitances of the deflection coil transformer and circuit as reected across the deection coil. This frequency of .selffoscillat-ionis such that the lirst-half cycle occurs ktime ts interval represented onV 'thegraphsonFig.2 Y Y' v As the oscillation tends to continue. beyond this half cycle, the electron discharge tubes of damper device 154 are caused to conduct and to damp deflection oscil-lzfition in the transformerdeeotion coil circuitV tof-cause a gradual decrease of current in they deflection coil instead of undesirable oscillatory variations of current at high frequency which disturb the linear variation of currentV therein. In this connection, it is to be noted, that different from known devices wherein the `grids of theV damping device are driven from the high potential side of secondary winding of the deilectionfcircuit .transclass B operation,A conduction occurs over of .the Y cycle. Hence, in most applications where. class B- operaa tion is employed, two tubes are used and are driven antiphase so that at least one tube isconducting .over Athe entire cycle.

In class C operation, conduction occurs over a portion ofthe cycle which is lless than 180. In the case of sine wave operation, class C operation accordingly requires a tuned plate circuit with sufficient `stored energy capa'-A bility to restore the sine wave voltager swing since plate current is drawn as a pulse over only ai small portion of the cycle.

Class AB operation Ais operation between class A and class B, i.e., a tube is operated to conduct less than.y 360 (the entire cycle) and more than 180 (a half cycle); Class AB operation, as so defined, is generallyaccepted as the generic term for describing operationwhere con duction occurs in the aforesaid mannen VClass AB operation has been broken down into two categories; class AB1 wherein all the conditions necessaryrfor operation are presentV and with .the further requirement that Vthe maxi-Y mum excitation is not sucient to draw-'grid current and class ABZ wherein all theconditions necessary'for class AB operation are present but wherein the grid draws current at the peaks of excitation andvthus establishes additional bias. i

In a deliection system wherein class A operation is emv ployed, i.e., the power tube conducts over the entire cycle, generally there is no need for a damper tube since the driver, i.e., the power tube is always conductingand is always connected to the deilection coil, VthroughY the transformer. Such arrangements are well known andl almost always employ feedback. The tube operation is relatively linear (at least such linearity is sought after), The tube generally is always connected to they loadk and, in effect, forces rthe load current to control.

Such class A operation deection'circuits vare `utilized f when the deection requirements are very small andthe 'Y 5 poor eliciency of the class A operation system canfbe tolerated. .Howeven where the deliection current requirement 1s considerable, then class A operationcould vrequire power tubes of a great size, e.g.% kw. to .l kw. of plate dissipation. Now, referring back to Fig. 2in curve D, -linejD2 -indicates thelevel' at which conduction the power tube draws plate current.

VT he voltage across the secondary winding 132 of tran-s." v

former 128 and deectioncoil 176 is similar to the Vc011- iguration of the voltage of curve D, exceptthat itspositive going portion is less steepand rises to'a smaller-peak.Vr

'If there were zero resistance in the transformerandtlie generator, i.e., cathode fol-` `In class A operation oi:v a' tube, conduction occurs over Y Y' follow under its:

isinitiatedin powv er tube 122. This is at about the 30% to`35%point of the positive going portion of the inputvoltagel to grid` 14S and this is the lportion of the scansion period that i T deection-coil, there would only be required as voltage across the deiection coil, a negative pulse of suitable amplitude vwith Ia width about equal to and occurring at the end of the period ts. This may be readily understood from the following.

Since the voltage across the deflection coil That is, the current is linearly proportional to time and there would be a perfect saw tooth wave of current through the deflection coil.

However, the resistance in the circuit changes Equa- Ition 1 to EL-I-RL (4) From Equation 4 it is seen that to the constant voltage,

there has to be added a component which increases with time. This is the reason that a small saw tooth voltage component is applied to the deflection coil.

Actually, the above analysis is quite simplified and approximate since there has been neglected many other losses such as core loss in both the transformer and deection coil, tube curvature etc., such losses not having the form of a constant resistance. In practice, the voltages are slightly distorted to obtain a linear current in the deection coil, i.e., a resultant linear scan of the target electron beam on the target itself.

At the instant that the power tube is rendered nonconductive, there are present the conditions necessary for a freely oscillating system with substantially all of the energy stored in the inductive branches of the system. At this instant, since the damper tube had already been rendered non-conductive after about the rst of the scansion period, the system is effectively completely free. Immediately, there commences the transfer of the energy in the inductive branches to the capacitive branches of the system and this transfer is complete after 1A. cycle of the free resonant frequency of the system. During this A cycle the swing, the voltage at the plate of the power tube rises to its positive peak and the voltage at the deection coil falls to its negative peak. The energy (reduced slightly by losses) is now transferred back to the inductive branches of the circuit, the transfer occurring during the next quarter cycle of the free resonant frequency. -Oscillation Itends lto persist (i.e., the negative going swing of the voltage at the plate of the power -tube and the positive going swing of the voltage across /th'e :secondary winding of the transformer, the voltage lacross the deflection coil and the voltage at the plates ofthe damper device). But at the instant of commencement of oscillation, the damper device was in a non-con- 'ducting state permitting the system to be free. As the -oscillation is initiated, a positive going voltage is applied "to the. grids of the damper device but it remains nonconductive because the plate voltage thereof went negative through so large an excursion and at such a rate that no conduction therein was possible.

With the completion of the first-half cycle of the free 'resonant frequency, as a resultof the oscillatory voltage,

the plate voltage at the damping device attempts to go positivej` Simultaneously vat this time, the control grids of the damper device arey positive relative to the cathode thereof. This results in momentary very heavy conduction in the damper device; substantially the entire spac charge electron plasma is drawn to the plate thus constituting a large load on the oscillating system. The oscillation is thereby arrested but the inductive branches of the stystem, at this instant, contain stored energy which is only slightly less (because of the losses occurring during the 1/2 cycle of oscillation) than they contained at the instant that the power tube was rendered non-conductive. This stored energy is now permitted to discharge into the damper device under the control of the voltage at the grids thereof. Conduction persists in the damper device for about the rst 2/3 of the scansion time, the wave form at the control grids thereof being such as to control this discharge of energy from the deilection coil so that a substantially linear current flows through the deflection coil. The conduction periods of the power tube and the damper device overlap by an appreciable yamount and the feedback automatically selectively operates on the control grid voltage of both the power tube and the damper device to provide a linear scan as a result thereof. It is to be observed that the grid voltages applied to the power tube and the damper device although of the same general wave form are of appreciably different amplitudes.

It is to be noted that damping device 154 is connected in shunt with the entire secondary winding 132 whereas coil 176 is connected in shunt across that portion of secondary winding 132 between the point designated by the numeral 174 and its lower end. By this arrangement, an auto transformer action is obtained. It has been found that such auto transformer action is, in general, essential in those applications wherein the A.C. voltage swing across the deflection coil for the required deflection current, is not sufficient to properly operate damper device 154. By stepping up this voltage through auto transformer action, proper damper device operation is obtained. In general, the leakage reactance between the two sections of the secondary winding must be minimized; however the small amount of unavoidable leakage reactance is offset by the feedback. The application to the grids 165 and 167 of damper device 154 of the output from a cathode follower in conjunction with the use of two tubes in parallel connection as shown in device 154 has been found to be advantageous in that it permits relatively large currents to ow in the damper device, particularly at that time when damping action is required. The parallel arrangement of adjustable resistors and 172 is a conventional means for adjusting centering by applying a DC. bias current through deflection coil 176. Choke coil 178 isolates the A.C. secondary currents from the centering circuit, the A.C. return circuit for the deection currents being from deflection coil terminal 177 through bypass capacitor 180, feedback voltage sensing resistors 199 and bypass capacitor 153 to the lower end 137 of secondary winding 132.

When the circuit of Fig. l is in use, variable resistor 78 in the plate circuit of degenerative amplifier 70 is the coarse control of linearity and variable resistor 34 in the output of saw tooth generator 10 is the fine control. By setting resistor 34 to about the center of its range and then adjusting resistor 78, there is a large range wherein all of the raster except the immediate lefthand edge is linear. Resistor 78 can be adjusted so that even the left-hand edge is also linear. Resistor 34 then gives a fine control over the left-hand edge linearity.

It has been found in practice that the following values are suitable for the circuit components in the circuit described in Fig. l. However, these values are being ymerely given as an example and it is to be understood that other values may be substituted for any or all of vthe components if desirable or necessary.

Transformer," primary 300 turns, secondary 360 turns y,single wave is 63.5 microseconds per period and that the discharge pulse for-discharging tube 12-of saw tooth y generator 10 has a Width of 6 microseconds andis a 30 volt Ipositive pulse. The graph B in Fig. 2 isa positive `going saw tooth wave of. 4.3 volts, the .pulse of graph ,C is ya positive pulse of 20.5 voltswithipoint C1 being 'at' 6%/2'v volts. The pulse of graphD is apositivepulse v 'pulse of graph E is an-S'l volt positive pulse with the point E1 being at 34 volts. f The current wave through thedeflection coilas shown in graph F as measured at point 200, Fig. 1 is 800 ma. The time included between thelarrows in graph F is approximately a l microsecond fis to be noted that saw tooth: wave generator is preceded by an amplier 300 for amplifying the horizontal drive'pulses. Since the input to saw `tooth wave generator 10 is apositive going rectangular pulse, the input i tothe control grid of ampliiier 300 is, a negative going pulsesuitablyhaving the same width as the input pulse l tothel sawtooth wavegenerator'.l vAlso it is seen that the poweramplier 120 now comprisestwo power tubes conv nected inpa'ra-llel to permit greater current' output therefrom. The'damper device-154 andfthe three deflection Y'coils aref connected in similar-arrangement as depicted faces-,e411

. n Resum fjl., Ohms 1,26 t 10 17.0,r 172 Y 50 56, 123, 181, 183 l r 100 1134 200 47, 59, 65 l 470 Y13s 630 Astig 1,600 lsz y2000 1 -481 Y 4,000 49,[112 10,000 f v f 20,000 76 24,000 Y 351 IS- `25,000 1 69 30,000 2'6, 54 100,000 28 v200,000 61, v63, '81, I86 t. a meg 1 24 I Y meg-- v 2.2 103 a ..meg.. 3 13 f meg 4.7 ZZ meg 5.6

rvCondensers 315, 62, y808, 102, 114, 121 .1 .Y. mf .1 v150, 151 1 p mf. 20 32 mmf Y s2 Y 1140 rf 100 v inmf t 1'53, '180, -mf v2,000

. Tub'es 12,42, 44, 72, 91, 106 1/2 12 AUTOI 59,6?, A122 1 6BQ6GA 154 6080 in Fig. 1. There is provided for eachA deiiection'cil variable vinductor dw for varying widths, a Vvariable re-H Y sistor dQ for adjusting the Qs of the respective coils y f Y and parallel combinations of resistors for the introduction of a controlled amount of vertical saw Vtooth voltage for adjusting skew. The operation of the'circuit of Fig. 3 is the same as that of Fig. 1.

While there have been shown particular embodiments of this invention, it will of course be understood that it is not intended to be limited thereto since many'mod'iiications both in the circuit arrangements and Vin the instrumentalities employed therein may be madeV and it is therefore contemplated by the appended claims to cover any such modications as fall within the true spirit and scope of the invention. l

What is claimed is: ,Y

1. A deliecting circuit for a cathode ray *comprising a' source of cyclically varying current, a transformer having a primary winding and a secondary winding, said primary v Y winding being connected to said source, arcathode ray deection coil connected in shunt with said' secondary winding, the current through said coil increasing to a predetermined value in accordance with the increase in i current from said source and the current fromsaid source being cut olf after the current through saidl coil rises to said predetermined value whereby the current in said deflection coil circuit is set into oscillation ata frequency determined by the elective inductance and capacitance of said deilection coil circuit, an electron discharge device including a cathode, a control electrode and,k

an anode for damping said current oscillations after the first-half cycley of oscillations, said damping device havv ing its anode to cathode path connected in shunt with said secondary winding, said source of cyclically varying lcurrent comprising means for generating affcyclically vvarying potential, means responsive 'tothe -appllcationfthereto of said cyclically Vvarying potential and a potential proportional to the current flowing through said coilffor providing a potentialin accordance with ythe difference ltherebetween, a power tube having an input and an output circuit, means for applying the output of said difference means to the input circuit of said power tube and to the control electrode of said dampingrdevice, said transformer coupling the output of said power tube to said deflection coil, said power tube and said damping det vice being chosen to have respective operating kpoints whereby said power tube is conductive through at least the latter half of the period between the end ofone of said first-half cycles of said oscillations and the beginning of the next of said rst-half cycles' and whereby saidV damping device isconductive through fat least the first K half of said period.

vf2. A dei'lecting circuit for a` cathode ray comprising ak source ofcyclicallyvaryingcurrenh atrans'former having a yprimary winding and asecondary winding, said pri-j' marywinding being connected to said source, a cathode ray deflection coil connected in shunt with said secondary winding, the current through said coil increasingto a predetermined value in Yaccordance with the increase in current from said source kand the current fromsaid source ythe'eiiective inductance and capacitance of said deection coil circuit, an electron discharge device including a cathode, a control electrode and an anode for damping 'saidcurrent oscillations after the irst-half cycleof said oscillations, said damping device having its Vanode to-Kcatlzi-` f. ode path connected in shunt with said secondarywinding,` 2

said source of cyclically varying current comprising means for 'generating a cyclically varying potential, rnietnsxre-ft sponsive to 'the application thereto of Ysaid cyclically" varying potential and a potential proportional tothe v current owing through saidco'cfor providinga potential,

acs-m44 in accordance with a difference therebetween, circuit isolation means, a power tube having an input and an output circuit, means for applying the output of said difference 4means to the input circuit of said power tube, and to the control electrode of said damping device through said isolation means, said transformer coupling the output of said power tube to said deiection coil, said power tube and said damping device being chosen to have respective operating points whereby said power tube is conductive through at least the latter half of the period between the end of one of said first-half cycles of said oscillations and the beginning of the next of said first-half cycles, and whereby said damping device is conductive through at least the first-half of said period.

3. A deiiecting circuit for a cathode ray comprising a source of cyclically varying current, a transformer having a primary winding and a secondary winding, said primary winding being connected to said source, a cathode ray deflection coil connected in shunt with one end of said secondary winding and at an intermediate point on said secondary winding, the current through said coil increasing to a predetermined value in accordance with the increase in current from said source and the current from said source being cut off afterthe current through said coil rises to said predetermined value whereby the current in said deflection coil circuit is set into oscillation at a frequency determined by the effective inductance and capacitance of said deflection coil circuit, an electron discharge device including a cathode, a control electrode, and an anode for damping said current oscillations after the first-half cycle of said oscillations, said damping device having its anode to cathode path connected in shunt with said secondary winding, said source of cyclically varying current comprising means for generating a cyclically varying potential, means responsive to the application thereto of said cyclically varying potential and a potential proportional to the current owing through the said coil for providing a potential in accordance with a difference therebetween, a power tube having an input and an output circuit, means for applying the output of said difference means to the input circuit of said power tube and to the control electrode of said damping device, said transformer coupling the output of said power tube to said deection coil, said power tube and said damping device being chosen to have respective operating points whereby said power tube is conductive thro-ugh at least the latter half of the period between the end of one of said rst-half cycles of said oscillations and the beginning of the next of said first-half cycles and whereby said damping device is conductive through at least the rst half of said period.

4. A deecting circuit for a cathode ray comprising a source of cyclically varying current, a transformer having a primary winding and a secondary winding, said primary winding being connected to said source,` a cathode ray deflection coil connected in shun-t with one end of said secondary winding and an intermediate point on said secondary winding, the current through said coil increasing to a predetermined value in accordance with the increase in current from said source and the current from said source being cut off after the current through said coil rises to said predetermined value whereby the current in said deflection coil circuit after rising to said predetermined value is set into oscillation at a frequency determined by the effective inductance and capacitance of said deflection coil circuit, an electron discharge device including a cathode, a control electrode and an anode for damping said current oscillations after the first-half cycle of said oscillations, said damping device having its anode to cathode path connected in shunt with said secondary winding, said source of cyclically varying current comprising means for generating a cyclically varying potential, means responsive to the application thereto of said cyclically varying potential and a potential proportional to the current owing through said coil for providing a potential in accordance-with the difference therebetween, a power tube having an input and an output circuit, impedance matching means, means for applying Athe output of said difference means to the input circuit of said power tube and through said impedance matching means to the control electrode of said damping device, said transformer coupling the output of said power tube to said deflection coil, said power tube and said discharge device being chosen to have respective operating points whereby said power tube is conductive at least through the latter half of the period between the end of one of said first-half cycles of said oscillations and the beginning of the next of said first-half cycles and whereby said damping device is conductive through at least the first-half of said period.

5. A deection circuit for a cathoderay as defined in claim 4 wherein said means for generating said cyclically varying potential is a saw tooth Wave generator.

6. A deflecting circuit for a cathode ray as defined in claim 4 wherein said diierence means is a difference amplier.

.7. A deiiecting circuit for a cathode ray as defined in claim 4 wherein said impedance matching means is a cathode follower.

8. A deecting circuit for a cathode ray comprising a source of cyclically varying current, a transformer having a primary winding and a secondary winding, said primary winding being connected to said source, a cath.- ode ray deflection coil connected in shunt with one end of said secondary winding and an intermediate point on said secondary winding, the current through said coil increasing to a predetermined value in accordance with the increase in current from said source and the current from said sourcel being 4cut off after the current through said coil rises to said predetermined value whereby the current in said deection coil circuit after rising to said predetermined value is set into oscillation at a frequency de'- termined by the effective inductance and capacitance of vsaid deection coil circuit, an electron discharge device vcomprising first and second plates, rst and second control electrodes, and rst and second common connected .cathodes for damping said current oscillations after the irst half cycles of said oscillations, said damping device having its respective anode to cathode paths connected in shunt with said secondary windings, said source of cyclically varying current comprising means for generating a potential having a saw tooth wave configuration, a difference amplifier responsive to the application thereto offsaid saw tooth Wave potential and a potential proportional to the current owing through said coil for providing a potential in accordance with the difference therebetween, a power tube having an input and an out,- put circuit, a cathode follower, means for applying the output of said dierence amplifier to the input circuit of said power tube and to the control electrodes of said damping device through said cathode follower, said transformer coupling the output of said power tube to said deflection coil, said power tube and said discharge device being chosen to have respective operating points whereby said power tube is conductive at least through the latter half of the period between the end of one of said irsthalf cycles of said oscillations and the beginning of the next of said first-half cycles and whereby said damping device is conductive through at least the first-half of said period.

9. A deecting circuit for a cathode ray as defined in claim 8 wherein said power tube is a vacuum tube pentode.

l0. A deecting circuit for a plurality of cathode rays comprising a source of cyclically varying current, a transformer having a primary winding and a secondary winding, said primary winding being connected to said source, a plurality of cathode ray deflection coils connected in shunt with the end of said secondary winding and an intermediate point on said secondary winding, the current .through said coils increasing to aV predetermined value in accordance with the increase in current from said source andthe current from said source being cut off after the vice including first and second cathodes, first and second vcontrol electrodes, and first and second anodes for damping said current oscillations after the first-half cycle of said oscillations, said damping device having its respective anode to cathode paths respectively connected in shunt with said secondarywinding, said Vsource of cyclically varying current comprising`v means for generating a potential having a saw tooth?.configuratiom a difference amplifier'responsive to Ilthe application thereto of the output from 'said'.sawtooth, wave generating means and a potential vproportional to the current'towing through said coil for providing a potential in accordance with the difference therebetween, a power 'tube having an input and an output circuit, a cathode follower, means forapplyin the output from said difference amplifier to both th control electrodes of said damping device through sai cathode follower and to the input circuit of said power3 tube, said transformer coupling the output of said power tube to said deflection coil, said power Vtube and said damping device being chosen to have respective operating points whereby said power tube is conductive atleast through lthe latter half of the period between the end of V one of said first-half cycles of said oscillations and thel' l beginning of the next of said first-half cycles and kwhereby said damping device is conductive at least through the rst-half of `said period.

1l. A deflecting circuitas defined in claim 10 wherein v said power tube is a double vacuum tube pentode. f

No references cited. 

